1. Field of the Invention
The present invention is directed to an electric polyphase motor, particularly for driving an indicator needle.
2. Discussion of the Background
Polyphase motors are, for example, described in European patent EP 587685.
State of the art step motors have a jerky movement, due to the fact that one magnetized pole of a rotor finds a privileged balanced state when it is placed opposite a stationary tooth, or when a transition between two magnetic poles is opposite a stationary tooth. As a result, a detent torque constitutes a periodic function of an angular position whose rate depends on a number of magnetic poles and on a number of stationary poles. In the current state of the art, it has been attempted to "smooth out" this function by increasing the number of poles. Nevertheless this involves greater mechanical complexity and higher manufacturing and assembly costs.